Patient-reported outcomes (PROs) in KEYNOTE-921: Pembrolizumab (pembro) plus docetaxel for patients (pts) with metastatic castration-resistant prostate cancer (mCRPC).
Authors: Daniel P. Petrylak, Raffaele Ratta, Nobuaki Matsubara, Ernesto Pablo Korbenfeld, Rustem Gafanov, Loic Mourey, Tilman Todenhöfer, Howard Gurney, Gero Kramer, Andre M. Bergman, Pawel Zalewski, Maria De Santis, Andrew J. Armstrong, Winald R. Gerritsen, Russell Kent Pachynski, Todd L. Saretsky, Sameer R. Ghate, Xin Tong Li, Charles Schloss, Karim Fizazi
Journal: Journal of Clinical Oncology (2023)

129 Background: The double-blind, phase 3, randomized KEYNOTE-921 trial (NCT03834506) showed that pembro + docetaxel did not significantly improve rPFS or OS for pts with mCRPC treated with prior next-generation hormonal agent (NHA) therapy. We present PROs for pembro + docetaxel vs placebo + docetaxel in KEYNOTE-921. Methods: Pts were randomly assigned 1:1 to receive pembro 200 mg or placebo IV Q3W (≤35 cycles) + docetaxel 75 mg/m 2 IV Q3W (≤10 cycles) and prednisone 5 mg orally BID. PROs were evaluated in pts who received ≥1 dose of study treatment and had ≥1 PRO assessment. FACT-P and BPI-SF were administered at baseline, Q3W until wk 24, Q6W until wk 72, then Q12W for ≤2 y. A prespecified secondary end point was time to pain progression (TTPP) based on BPI-SF. Prespecified exploratory end points included least squares mean (LSM) change from baseline to wk 27 for FACT-P total and subscale scores (FACT-G total, TOI, FAPSI-6, FWB, PWB, and PCS) and wk 24 for BPI-SF scores (pain interference, pain severity, and worst pain), and time to deterioration (TTD) and overall improvement rate in FACT-P total and subscale scores. Differences were evaluated using 2-sided nominal P values not controlled for multiplicity. Results: Of 1030 pts enrolled, the PRO analysis population included 1028 (n = 514 in each arm). At the prespecified final analysis, median time from randomization to data cutoff of June 20, 2022, was 22.7 mo (range, 12.1-36.7). Completion rates for FACT-P and BPI-SF were &gt;78% at baseline, &gt;65% for FACT-P at wk 27, and &gt;63% for BPI-SF at wk 24. Median TTPP was 21.1 mo (95% CI, 13.7-NR) for pembro + docetaxel vs NR (95% CI, 13.8-NR) for placebo + docetaxel (HR, 1.05 [95% CI, 0.77-1.43]). No LSM differences were observed in FACT-P total scores with pembro + docetaxel (–5.31 [95% CI, –7.02 to –3.61]) vs placebo + docetaxel (–3.89 [95% CI, –5.59 to –2.19]) or BPI-SF scores. Median TTD in FACT-P total scores was 21.8 mo (95% CI, 20.0-NR) for pembro + docetaxel and NR (95% CI, 11.1-NR) for placebo + docetaxel (HR, 1.09 [95% CI, 0.88-1.35]). No differences were observed for TTD in FACT-G total, TOI, FAPSI-6, FWB, PWB, and PCS scores between groups. A numerically lower proportion of pts receiving pembro + docetaxel (39.9%) had improved + stable FACT-P total scores compared with placebo + docetaxel (45.3%). FACT-P and BPI-SF scores were generally maintained across all evaluated time points up to wk 81. Conclusions: HRQoL and disease-related symptom scores at all analyzed time points, as well as TTD and TTPP, were similar between the 2 trial arms. These data suggest that pembro + docetaxel did not negatively impact QoL in pts with mCRPC treated with prior NHA. Clinical trial information: NCT03834506 . [Table: see text]